I recently had surface dripline run along the strips in my backyard and I was trying to calculate the inches per hour. The number I come up with seems a bit low, so I thought I’d post my calculations and see if anyone sees an error.

Much of the strip is about 3’ wide and has 2 driplines running down it spaced 1’ apart. I realize this may not be ideal, the space between the 2 lines will get more water than the space outside the 2, but that’s the way they got laid out by the landscaper. The line has 1/2 g/hr emitters spaced every 12". So if I think about a 10’ length it will have 20 emitters giving 10 g/hr. 10 gallons is 2310 cubic inches. This is spread over an area of 30sq feet, and with 144 in^2 per foot^2 the area is 4320 in^2. Each sq inch gets 2310/4320 = .53" of water per hour.

Your numbers look right to me (/ (* 96.25 (/ 10. 60.)) 30.) = 0.534722 … if the water was getting evenly distributed over 30 sq ft. Since drip emitters are point source irrigation, I’d run the system and see how much of the area is really saturated & use that covered area. I bet your application rate will be higher.